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An introduction to the hormones in the male reproductive system


Background
  • Male sex hormones are also known as androgens.
  • Spermatogenesis: process in which male sperm cells undergo meiosis (video later).
  • Reproductive organs/cells used in the male reproductive system and their basic functions:
    • External:
      • Penis: used for sexual intercourse.
      • Scrotum: protective sac containing testicles.
      • Testicles: produce testosterone (discussed later).
    • Internal:
      • Urethra: tube that carries urine and semen from, respectively, the bladder and testicles.
      • Prostate gland: helps expel semen through the urethra by producing fluids.
      • Seminiferous tubules: responsible for producing sperm cells through spermatogenesis.
      • Interstitial cells (AKA Leydig cells): secrete testosterone, androstenedione, and dehydropiandrosterone. Located in testicles.
      • Sertoli cells: nurture developing sperm cells through stages of spermatogenesis.
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Functions of the male reproductive system:
  • Producing, maintaining, and transporting sperm.
  • Produce and secrete sex hormones.

Video #1:





Hormones involved (5):
  • Released by anterior pituitary gland:
    • Follicle stimulating hormone (FSH): stimulates production of sperm in seminiferous tubules.
    • Luteinizing hormone (LH): stimulates testosterone production by interstitial cells.
  • Released by interstitial cells:
    • Testosterone: stimulates spermatogenesis, associated with sex drive and secondary sex characteristics (growth body hair, facial hair, strengthening of bones, thickening of skin, etc.).
  • Released by sertoli cells:
    • Inhibin: feeds developing sperm cells. Also, slows release of FSH and LH if required (negative feedback system).
  • Released by hypothalamus:
    • Gonadotropin releasing hormone (GnRH): tells pituitary gland to release LH and FSH. Also, controls sperm production and testosterone levels.

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Associated problems:
  • Kallmann syndrome: congenital anosmia or hyposmia (inability to smell). This happens because of defects to the hypothalamus, affecting production of GnRH. In turn, GnRH can no longer regulate production of FSH and LH.
  • Delayed puberty: in young adults, a lack of FSH and LH may be the cause to a delay in puberty.

Video #2:





Labelling:
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Scrotum -> Epididymis -> Vas deferens -> (by seminal vesicle) -> Prostate gland -> Cowper's gland -> Urethra

Citations: